HomeMy WebLinkAboutSDP201100084 Review Comments Final Site Plan and Comps. 2012-03-06i"
,. `IRGINZP
COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road, Room 227
Charlottesville, Virginia 22902 -4596
Phone (434) 296 -5832 Fax (434) 972 -4126
Project: Westminster Canterbury Monticello Building Expansion
SDP201100084 (Final Site Development Plans)
WP0201100105 (Water Protection Ordinance)
Plan preparer: Timmons Group [fax 295 -83171
Owner or rep.: Westminster Canterbury of the Blue Ridge [fax 972 -31731
Plan received date: 3 Jan 2012
(Rev. 1) 21 February 2012
Date of comments: 1 Feb 2012
(Rev. 2) 6 March 2012
Reviewer: Michael Koslow
The Final Site Plans (SDP201100084) and Water Protection Ordinance plan set and
computations (WP0201100105) submitted 21 February 2012 have received Engineering
Review and do not appear to meet Albemarle County minimum checklist items for approval.
Please adequately address the following comments for final approval:
A. Existing Conditions Information (WP0201100105)
1 Please identify the date of topography.
(Rev. 1) Comment has been addressed.
2. Please identify a benchmark location and elevation for topography. An existing utility or other known
position will suffice.
(Rev. 1) Comment has been addressed.
3. Please be consistent with contour interval labeling (i.e. every 1', 2' or 5'; prefer 2' intervals).
(Rev. 1) Comment has been addressed.
B. Proposed Plan View Information (SDP201100084)
1. Please provide a detail for retaining wall which includes safety railing for retaining walls over 4' high.
(Rev. 1) Comment remains until detail is included. Please note this detail will need to be
referenced into and included with the plan set.
2. Please provide unobstructed sight distance lines to demonstrate sight distance > 10' x speed limit from
all entrances measured from a point 10' off the edge of the intersected street.
(Rev. 1) Comment remains pending approval of site distance waivers submitted 21 February
2012 to Zoning Administrator.
3. Please revise all entrance radii to minimum of 12.5'
(Rev. 1) Comment has been addressed.
4. Please revise all parking stall widths to 10', a requirement for aisle width < 24'.
(Rev. 1) Parking stall widths should be consistent within one aisle for constructibility. Please
provide an abrupt aisle width transition at south end of Bishops Ridge Dr. at the 5' radius at the
south end of the parking area and reduce parking widths to 9'.
5. Please revise all sidewalk widths adjacent to parking to 6'
(Rev. 1) Comment has been addressed.
Engineering Review Comments
Page 2 of 5
7. Please provide bumper blocks for parking stalls adjacent to 5' wide sidewalk.
(Rev. 1) Comment has been addressed.
8. Please show flow arrows for all proposed and existing storm sewers.
(Rev. 1) Comment has been addressed.
9. Please label all existing and proposed street names.
(Rev. 1) Comment has been addressed.
10. Please label all curb radii for all proposed entrances and intersections.
(Rev. 1) Comment has been addressed.
11. Please provide dimensions and labels for all pavement markings.
(Rev. 1) Comment has been addressed.
12. Please identify building loading zone and dumpster locations if applicable (or comment if not).
(Rev. 1) Comment has been addressed.
13. Please add "CG -12" label at curb ramp by building.
(Rev. 1) Curb profile transition distance or rate has not been specified. Please provide a detail
or taper rate to delineate how transition takes place. Alternately, please provide dimensions and
limits for the begin and end curb taper locations. Refer to 12:1 CG -12 curb transition on VDOT
Road and Bridge Standard (203.05) for an example.
14. Please extend sidewalk at southwest corner of the sidewalk. Current crosswalk appears to connect to
an existing driveway. Please extend the sidewalk and provide a curb ramp beyond the existing
driveway.
(Rev. 1) Comment has been addressed.
15. Please extend curb at curb ramp at southwest corner of the parking lot to reduce washout of adjacent
earth.
(Rev. 1) Comment has been addressed.
C. Plan Detail Information (SDP201100084)
1. Please provide pavement design calculations.
(Rev. 1) Heavy Duty Asphalt Pavement Section on sheet C0.1 does not describe the derivation to
ensure that the pavement thicknesses shown are sufficient for the design traffic. Please refer to
2009 VDOT Pavement Design Guide For Subdivision And Secondary Roads In Virginia,
Appendix IX: Flexible Pavement Design Worksheet for New Subdivision Streets. It appears
three pavement sections are included:
a. Pavement adjacent to curbs as identified in VDOT Standard Curb 4" CG -3 Curb detail and
VDOT Standard CG -2 Curb detail on sheet C0.1
b. Heavy Duty Asphalt Pavement Section on sheet C0.1
c. Concrete Pavement Section as referenced to Architectural Plans on sheet C2.0.
Please expand legend on sheet C2.0 or otherwise delineate limits of above proposed pavement
sections. Please provide Concrete Pavement Section detail. Please provide the derivation to
ensure that the pavement thicknesses for each of the three sections proposed is sufficient for the
design traffic.
2. Please provide a detail for all proposed drainage structures crossing all proposed retaining walls.
(Rev. 1) Please provide Drainage Profile for Structures 304 & 306 at sufficient scale to verify
there is no conflict with the proposed retaining wall footer. Please label the proposed retaining
wall footer.
3. Please provide Albemarle County general construction notes.
(Rev. 1) Comment has been addressed.
4. Please provide a curb transition detail near Structure #100.
(Rev. 1) Please refer to response B13.
Engineering Review Comments
Page 3 of 5
D. Drainage Profiles (WP0201100105)
1. Please provide a VDOT designation for each structure.
(Rev. 1) Please label Structure #s 200 and 306 in Drainage Profiles. Please provide VDOT
Designations for Structure #s 102, 300, 304, 304, and 308 in Drainage Profiles (they appear to be
either MH -1s or MH -2s). Please provide a detail for circular grate for Structure #s 306 and 312
which fits a standard VDOT manhole casting. Please label 18" ADS Basin Structures near
Structure #100 and provide a detail for these structures. Please provide a drainage summary
delineating drainage structures proposed for this project [18- 32.6.d4]. Please provide
designations equivalent to VDOT designations for the circular grate and ADS Basin Structures.
2. Please provide a throat length for each drop inlet.
(Rev. 1) Comment has been addressed.
3. Please provide a grate type for each grate inlet.
(Rev. 1) Comment has been addressed.
4. Please provide concrete inlet shaping for any structure with a 4' or greater drop.
(Rev. 1) It appears that Structure #s 102, 104, 108, 110, 200, 202, 300, 302, 304, 306, 308, and
310 have a 4' or greater drop. Please add "IS -1" labels to these structures to clarify needed
concrete inlet shaping for these Structures and any others with a 4' or greater drop.
5. Please provide end sections or endwalls on all pipe outlets.
(Rev. 1) Comment has been addressed.
6. (Rev. 1) It appears the outlet for Structure #102 would need to be lowered to el. 575.02 or
otherwise provide positive flow from pipe #103 to pipe #101. Also, please label structures and
HDPE pipes from which drain trench drains connect to pipe #109 and Structure #102. Please
re -route HDPE pipe to Structure #108 or provide another drainage structure at junction for
cleanout purposes. Please clarify invert labels for Structure #102 (currently shows Inv. In
575.40 (1 (8)).
E. Drainage Computations (WP0201100105)
1. After Limits of Disturbance are calculated, will need to verify the drainage areas identified in the
drainage computations.
(Rev.1) Comment has been addressed.
2. Proposed drainage outlets to three independent sources. Please revise computations to reflect areas
draining to Pond, existing bioretention area, and untreated outlet at US -250 drainage ditch.
(Rev. 1) Please show the overall concept, including conveyance and the existing stormwater
facilities on the plans. For example, sheet C4.2 shows disconnected areas. Show the storm
drains which connect them, and the ponds and biofilters to which they drain. The computation
should include a verification of the existing conveyance to the stormwater facilities (MS -19). It
should also include the effect on the existing stormwater facilities. See section G comments.
Also note the Stormwater Management Narrative and computations refer to sheet C4.3 for
drainage areas (it appears reference should be to sheet 4.2)
F. Stormwater Management Plan (WP0201100105)
1. Please provide as -built plans for existing pond and biofilter to be used for stormwater management for
the Monticello Building Expansion.
(Rev.1) Comment has been addressed.
2. Please provide a proposed drainage map to demonstrate area which drains to the three independent
sources (see Comment E2). Please include the direction the building roof drains outlet with the
drainage map.
(Rev.1) Please see comment E.2.
Engineering Review Comments
Page 4 of 5
G. Stormwater Management Computations (WP0201100105)
1. Please provide computations to demonstrate a better post - development condition for the portion of the
project which drains to US -250 drainage ditch.
(Rev.1) Area 2: We recommend that you use a curb inlet stormwater management device like a
filterra to treat this area, rather than leave it untreated. MS -19 must be considered in this area.
We have found that balancing the rate computations may not be adequate, and you still need to
investigate the downstream system for potential existing problems.
2. Please provide computations to demonstrate water quality and detention requirements are met for the
portion of the project which drains to the existing bioretention area.
(Rev.1) Area 1: It appears that the impervious area draining to the biofilter has doubled, at
least. (This was not clear in the computation.) There should be no increase to this already
inadequate biofilter, unless you are going to redesign this biofilter, which is designed to 0.5" of
water over the impervious surfaces draining to it. As we discussed in our meeting, the County is
also very sensitive to the amount of water draining to this downstream neighbor, and would
prefer to be very sure of no increases, so balancing the computations to try and equalize the rate
and volume is not good practice.
3. Please revise computations for a reduced area of increased impervious surface which drains to the
existing pond.
(Rev.1) Area 3: Please show the entire conveyance to the pond, and check per MS -19. The pond
volume appears adequate for the area and increase in impervious surface.
H. Erosion and Sediment Control Plan (WP0201100105)
1. Please provide soils descriptions and label soil divides on plans.
(Rev. 1) Comment has been addressed.
2. Please include Albemarle County erosion control notes.
(Rev. 1) Please separate out sheets C5.0, C5.1, C5.2 into a separate Erosion & Sediment control plan
set. Please include the erosion control notes in this plan set. Albemarle County keeps Site
Development Plan sets (permanent) separate from Erosion & Sediment Control plan sets
(temporary). This could also be done with the stormwater management plan (WP0201100105).
3. Please include Stormwater Runoff Considerations in the Erosion and Sediment Control Narrative
before the Sequence of Installation (see VESCH Checklist for Erosion and Sediment Control Plans p.
VI -13).
(Rev. 1) Comment has been addressed.
4. Culvert inlet protection identified for existing inlet near proposed Structure 100 will be graded over.
A sediment trap will be required near Structure #100. Please also provide sediment trap sizing
calculations. Please call for clarification.
(Rev. 1) Sediment trap side slopes and capacity are adequate. However, the outlet width for this
4' tall sediment trap should be a minimum of 3 feet ( VESCH Plate 3.13 -1).
5. Please change the "CIP" label downstream of Structure #100 to "OP" on sheet C5.1 as outlet
protection will be required at the outlet of this existing culvert during construction.
6. Identify staging areas and parking area for contractor.
(Rev. 1) Comment has been addressed.
7. Please label the limits of disturbance encompassing all clearing, grading, entrances, staging and
parking areas, areas where sediment laden runoff will cross, or any construction related activities.
(Rev. 1) Comment has been addressed.
8. Please show location for Construction Office on plan.
(Rev. 1) Comment has been addressed.
Engineering Review Comments
Page 5 of 5
9. Please include Dust Control (symbols) for disturbed ground areas.
(Rev. 1) Comment has been addressed.
10. Please include Temporary and Permanent Seeding (symbols) for disturbed ground areas.
(Rev. 1) Comment has been addressed.
11. Please identify existing drainage divides.
(Rev. 1) Comment has been addressed.
12. It appears silt fence is proposed across construction entrance near existing parking lot. Provide
Temporary Right of Way diversion instead.
(Rev. 1) Comment has been addressed.
13. Show proposed silt fence turned up at ends near proposed garden area (at ends of contour elevation
588 feet).
(Rev. 1) Comment has been addressed.
14. Please show silt fence below wall (recommend 5' — 7' for construction access).
(Rev. 1) Comment has been addressed.
15. Provide temporary diversion dike instead of silt fence where silt fence is proposed south of proposed
parking garage entrances.
(Rev. 1) Comment has been addressed.
16. Block or seal existing inlet and trench drain at east side of existing parking area prior to removal of
existing inlets at parking lot entrance. This will prevent mud /soil from entering the storm sewer
system.
(Rev. 1) Comment has been addressed.
17. Please provide dimensions and stone sizes for outlet protection at Structure #100 shown on sheet C5.2.
(Rev. 1) Comment has been addressed.
18. Show soil stockpile location or note how excavation will be stockpiled during construction.
19. Address public safety during excavation for parking garage (e.g. provide safety fence).
(Rev. 1) Comment has been addressed.
20. "Stormwater inlet protection" detail on sheet C5.0 not recommended. Recommend providing inlet
protection with overflow capabilities (see VESCH Plate 3- 07.8).
(Rev. 1) Comment has been addressed.
21. (Rev. 1) This project is in the Piedmont area [ VESCH Plate 3.32 -1]. Please revise Permanent
Seeding, Std. & Spec. 3.32 on sheet C5.0.
Once these comments have been addressed, please submit 2 copies of the revised plans, calculations, and
narratives to Community Development Engineering along with the required review fee and transmittal
form.
Community Development Engineering is available from 2:30 -4 PM on Thursdays to discuss these review
comments. Please contact Michael Koslow at 434 - 296 -5832 ext. 3297 or email mkoslow @albemarle.orc
to schedule an appointment.
[17- 204.f] An application for an erosion and sediment control plan that requires modifications, terms, or conditions to be
included in order for it to be approved shall be deemed to be withdrawn if the owner fails to submit a revised plan addressing the
omitted modifications, terms or conditions within six (6) months after the owner is informed of the omitted information as
provided under paragraph (B).
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